Symptomatic osteoarthritis (OA) of the knee affects millions of Americans. Although isometric strengthening maintains function and reduces pain among people with OA, only 2% exercise. We propose that the devise will realize a popular, isometric quadriceps/hamstring strengthening program for use at home. By incorporating our patented force sensor, this product will build adherence through continuous readout of isometric force. In operation, the user turns on the device and chooses a force threshold, place the device between the ankles while comfortably seated, and presses the legs together. The device automates exercise thereafter, audibly cueing when to apply force, rest and stop. During phase I, we will add an auto-off and event counter to existing microprocessor circuitry, and fabricate a rugged, attractive housing. Extensive electrical, mechanical and material testing will follow to insure feasibility. Lastly, between 5-10 subjects will receive isometric quadriceps/hamstring strengthening under supervision for eight weeks. We will compare pre-and post-trial isometric strength and quantify pain/stiffness/disability score (WOMAC). Data will determine power required to establish significance in Phase II clinical trials, which will investigate strength, function and adherence improvement with the device used unsupervised at home. PROPOSED COMMERCIAL APPLICATIONS: A home exercise program built around an isometric exercise device could be of enormous benefit to the estimated 7.5 million people with painful knee osteoarthritis, the umber expected to double by 2020. If it is positively demonstrated to motivate consumers to exercise, resulting in health benefits (increased strength, decreased pain and disability), then this product could certainly be commercialized successfully. Insurance reimbursement approval might follow positive outcomes of an SBIR phase II, leading to an expected high market penetration and rate of return. Market penetration could approach 5 percent even without insurance reimbursement, resulting in a market of greater than 50 million dollars.